Known cam follower assemblies typically include a rotating cam and a roller tappet including a roller supported by an axle mounted in a housing. The roller, which is configured to ride along the rotating cam, is rotatably mounted on the axle, which is retained in the housing. One type of roller tappet includes a fixed axle including staked ends such that the axle is non-rotatably fixed to the housing. Another type of roller tappet includes a floating axle with enlarged ends that axially retain the floating axle in bores on the housing such that the floating axle is configured to rotate relative to the housing.
Floating axles typically provide improved wear distribution compared to fixed axles, i.e. staked-end axles. During operation, fixed axles can experience relatively higher loading and wear along specific axle segments than floating axles. Accordingly, floating axles are sometimes used instead of fixed axles due to a generally more even wear distribution. However, floating axles can also fail to rotate properly during operation. Rotation of a floating axle can be interrupted due to a lack of precision machining of the housing bores that accommodate the axle or the axle itself. For example, the housing bores or the axle may be out-of-round or may include a high surface roughness which causes friction and inhibits or prevents relative rotation. In these situations, the axle does not rotate or gets stuck in a particular angular position, effectively producing a fixed axle which is susceptible to uneven wear distribution.
It would be desirable to provide an improved bearing interface between a floating axle and a housing for a roller tappet that prevents uneven wear distribution.